I used to get the same reaction when I fired my 454 Casull at an indoor range. One time it actually knocked the dust off the light fixtures LOL. You should have seen them when I fired up the 500S&W magnum! Believe it or not I get the biggest surprised reactions to my 22mag. pistol. It shoots out flames about a foot long.

I just bought one recently and found the same thing with my bore. It shoots fine and has good accuracy but the bore looks similar to your description. It's the roughest bore I've seen in a new gun. Seems to have longitudinal scratches running with the lands and grooves. It looks like maybe the boring bar had a rough cutter on it. All of the lands and grooves seemed to have them. I have had other Rugers and they usually have pretty descent bores. As good as it shoots I doubt they would replace it if I send it back.